Concrete form tie having flexible threads and associated bolt and method of making said tie



Jan. 12, 1965 3,164,878

D. M. BERG CONCRETE FORM TIE HAVING FLEXIBLE THREADS AND ASSOCIATED BOLTAND METHOD OF' MAKING SAID TIE Filed July 5, 1963 @as a l INVENTOR Al//D M. B15/P6 *ggf/fg@ United States Patent O i 3,164,873 CONCRETE FRM''IIE HAVEN@ FLEXIBLE THREADS AND ASSCIATED BIII AND METHGD F MAKING SAID'IIE j David M. Berg, 2024 Ardin Brive, Norristown, Ia.

' Filed duly 5, 1963, Ser. No. 292,866

2 Claims. (Cl. 25--l3l) This invention relates to a tie `and anassociated bolt securable to a form and more particularly to an improvedtie and bolt adapted to-hold together a form into which is pouredconcrete, and itis an object of this invention to provide an improvedconcrete form tie and bolt and an improved method of, makin-g the tie.

Further, this invention relates to tieswhich are intended to `hold apair of laterally spaced, opposed walls of a form (intowhich is to bepoured concrete) against any tendency of the walls to move during andafter the pouring of the concrete-therein. i

The known ties for use with such forms have threaded portions at theiroppositeV ends into which are threaded bolts forsecuring the ties to theforms. Both during assembly and disassembly of the forms, with theknownties, the bolts must berotated, inthe conventional manner, toaccomplish'threading during assembly and to ac-V complish unthreadingduring` disassembly. Such threading andl unthreading are performedmanually, and with the present high cost of construction labor, it isdesirable to provide a tie to which the bolt can be assembled withoutthis time consuming threading. It is, therefore, a further object ofthisinvention toprovide 'a tie cons tructed so that the bolt can beassembledthereto quickly and without the previously indicated threading.

Inoue embodiment of myvinvention the threads at the opposite ends of atie are formed as parts of coils and the threads are flexible andresilient, the coil being formed from a strip of spring steel (or othersuitable material) and supported by rods.v Bolts having rounded leadingnoses arev then inserted through holes in the forms and t pushed (with asufficient force) axially into the coils and during this insertionthebolt threadsflex back and forth, permitting full lengthwise or axialentry yof the bolt into the coils (until the boltheads abutthe forms),but at the end of such insertion,`the coilthreads prevent lengthwiseretraction of the bolts. However, when it is desired to remove thebolts, they may be removed by rotating them in the uuthreadiugdirection, in the conventional unthreading manner.

The foregoing and other objects of theinvention, the principlesV of theinvention, and the best mode in which I have'contemplated applying suchprinciples will more;

` lustrated in FIG. l showing the right hand coil in section and aportion of the right hand bolt;

FIG. 3 is an enlarged elevation view of the right hand portion of thetie illustrated in FIG. l;

ice

15, the walls 12 being held in spaced relation by my improved tie I6.

The tie 16 comprises 4 coextensive steel rods 1S welded incircumferential, spaced relation to each other about the cylindrical,outer surfaces of helical coils 2t) and 22, the coils 20 and 22 beingspaced from each other and secured to the rods at the opposite ends ofthe rods, as illustrated in FIG. 1, and being engaged by inserts orbolts Y 24 and 26, respectively, Vwhich extend through suitable holes 27in the form, the coils andV holes being axially l aligned.

The coils 2t) and 22 are similarly constructed and the descriptionhereinafter (for brevity) will be in termsof one coil only, the coil 22.

The coil `22 is formed from one continuous, longstrip 3@ of suitablyresilient material, such as spring steel, FIG.

6, which is initially at. The left hand portion 32 of the strip 3d issuitably deformed and bent downwardly and at a slant with the remainderor root 33, as illustrated in FIG. 5, the left hand portion becoming thecoil projections or threads 32, hereinafter referred to as threadsv 32,after the strip 32 is helically wound to form Vadjacent coil turnshaving a suitable thread lead and depth.

The coil is wound, as illustrated in FIGS.2 and 5, so that adjacent coilturns abut. Y That is, as illustrated in FIG. `5, the right hand edgeportion 34 ofthe root 33 abuts a portion of the thread 32 of theadjacent coil turn and to facilitate the flexing of the threads 32 therightY hand edge portion may be chamfered, as illustrated, but in anyevent a sufcient portion of the-thread 32 remains free below theaforementioned abutment to flex Vback and forth,; as hereinafter furtherreferred .to in more detail.

Referring to FIG. 2 there is illustrated the bolt26 after it has beeninserted into the coil 22 to its full extent and FIG. 2 also illustratesthe initial or rest position of the threads 32 when they restrain axialmovement of thebolt 26 in the retractingdirection. FIG. 5 illustrates aportionof the bolt 26 and the coil 22 during insertiony of the bolt26atwhich time the force on thekbolt pushing it into the coil causes thebolt threads 38, the bolt threads 38 and the coil threads 32 engagingeach other attheir tip portions only, to ex the coil threads 32 from thedotted position in FIG. 5 to the lfull line position and back and forthbetween thesev positions as the crests ofthe bolt threads 38 pass thecoil threads 32.

Y The bolts have threads which in cross-section have the shape of aninverted V which has an included angle of B of the coil threads and boltthreads, respectively, also FIG. 4.*is an end 4view taken along thelinev 4 4 in FIG. 3;k

FIG. 5 is a longitudinal sectional view,'butfurther en- ,isformed 7' jReferring to the drawings, a form lidisillustrated'de- I fined bysuitable at, opposedpanels or walls I2 secured Y to suitableVerticalestuds 14 and horizontal whale pieces j larged, `of aportionV ofthe structure illustrated iufFIGfZ; Hand. I j FIG. 6 isa top view of ametal strip from which the Vcoil to provide a space between the bolt andthe coil root into jointlydene an included angle of less than as also dothe surfaces C and D, of the coil threads and bolt threads,respectively, when the coil threads are in their initial or restposition, i.e., the full line position of FIG.

-2 and the dotted line position of FIG. 5. Further, the

length of the coil threads 32 relative to the bolt threads is such thatif axial retraction by an axial force on the bolt only is attempted, thethreads 32 will tend to wedge into the V-shaped space between the boltthreads.

Even if the coil threads 32 are Anot long enough to ac-V complish theaforementioned wedging, the forcerequired tofurther bend the coilthreads to the right (in FIG. 5)

vfrom the initial (dotted) position is greater than that to which thethreads may dex upon insertion of the bolt.

alegar/s To facilitate the ilexing of the coil threads I prefer to cutthe left hand margin of the strip 30 (which will form the threads 32)before the strip 30 is coiled in a manner to form spaced teeth 40 whichare wider at their roots than at their tops and separated from eachother hy a space of the same size but inverted.

Also, to expedite the entry of the bolts into the coils, I form thebolts with well rounded noses 45 at their forward portion and the rearportion of each bolt is provided with the usual bolt head 46 under whicha washer may be placed if desired. Only the forward end of the bolt isthreaded, a somewhat longer length than the length of a coil, theremainder of the bolt between the head and the threaded part beingUnthreaded and preferably of about the same diameter as the outerdiameter of the threaded part. l

Preferably, the coil ties are welded to the rods so that the rods extendslightly out beyond the coils, as illustrated in FIG. 2.

While not illustrated, the projections which engage the bolts need notbe in the form of threads and could simply depend from circular rings,i.e., a series of stacked washers or rings having inturned projectionscould be substituted for the coils. In such event, the projections wouldextend vertically, radially inwardly (and not on a slant).

`The associated bolts need then have only a series of spaced, shoulders(not threads) rounded at the top to aid in camming up the projections.The bolts could then be inserted axially and withdrawn axially byapplying to the bolts forces in the proper direction sufficient to flexthe projections out of restraining engagement with the shoulders. Thematerial of the projections and their resilience would have to be suchthat this force, however, would have to be a greater force than iscontemplated will be applied to the bolts by the form (under pressure ofthe concrete), as otherwise the ties would not serve any useful purpose,In this embodiment theend washer is coterininous with the rods at oneend and a sufficient number of washers are used sothat at the other endno bolt shoulder is unengaged by a washer. With such an arrangement noconcrete will come into engagementwith the bolt shoulders, as otherwiseit would ,be diicult to withdraw the bolt if a bolt shoulder had becomeembedded in concrete. It should be noted that where a threaded bolt isused, as in the prior embodiment, if concrete does engage the boltthreads, by unthreading, the bolt may be removed.

Having described my invention, I claim 1. In a concrete form tie'andbolt assembly, a plurality of coextensive rods, twohelical coils ofresilient strip material secured to said rods one at each of the endportions of the rods, said coils having spaced resilient portions bcntdownwardly at a slant to constitute thread portions, two bolts one ofwhich is associated with one of said coils and the other with the otherof said coils, each bolt having a threaded surface defined by invertedV-shaped threads and V-shaped spaces, the coil threads and the boltthreads being so related that, when assembled, the included anglebetween the adjacent, opposed surfaces of one coil thread and one boltthread is less than 90 as is also the included angle between adjacentbolt threads, the bolt thread outer diameter being less than the coilroot inner diameter, whereby the bolt may be readily inserted into theassociated coil by forcefully moving the bolt axially into theassociated coil at which time the coil threads spring back and forth asthe bolt threads enter, but a force on the bolt in the direction toretract the bolt will tend to ex the coil threads radially inward intowedging, locking engagement with the V-shape formed by adjacent boltthreads.

2. In a concrete form tie and bolt assembly, a plurality of coextensiverods, two helical coils of resilient strip material secured to said rodsone at each of the end portions of the rods, said coils having spacedresilient portions bent downwardly at a slant to constitute threadportions, two bolts one of which is associated with one of said coilsand the other with the other of said coils, each bolt having a threadedsurface, the bolt thread outer diameter being less than the coil rootinner diameter, whereby the bolt may be readily inserted into theassociated coil by forcefully moving the bolt axially into theassociaated coil at which tim the coil threads spring back and forth asthe bolt threads enter, but a force on the bolt in thedirection toretract the bolt will tend to flex the coil threads radially inward intolocking engagement wit the bolt threads.

References Cited by the Examiner UNETED STATES PATENTS 1,238,696 8/17Mumford 25-131 1,826,221 10/31 Pearson 85-36 1,970,946 8/34 Schenk25-131 FOREIGN PATENTS 112,552 2/41 Y Australia.

MICHAEL V. BRINDISI, Primary Examiner.

2. IN A CONCRETE FORM TIE AND BOLT ASSEMBLY, A PLURALITY OF COEXTENSIVERODS, TWO HELICAL COILS OF RESILIENT STRIP MATERIAL SECURED TO SAID RODSONE AT EACH OF THE END PORTIONS OF THE RODS, SAID COILS HAVING SPACEDRESILIENT PORTIONS BENT DOWNWARDLY AT A SLANT TO CONSTITUTE THREADPORTIONS, TWO BOLTS ONE OF WHICH IS ASSOCIATED WITH ONE OF SAID COILSAND THE OTHER WITH THE OTHER OF SAID COILS, EACH BOLT HAVING A THREADEDSURFACE, THE BOLT THREAD OUTER DIAMETER BEING LESS THAN THE COIL ROOTINNER DIAMETER, WHEREBY THE BOLT MAY BE READILY INSERTED INTO THEASSOCIATED COIL BY FORCEFULLY MOVING THE BOLT AXIALLY INTO THEASSOCIAATED COIL AT WHICH TIM THE COIL THREADS SPRING BACK AND FORTH ASTHE BOLT THREADS ENTER, BUT A FORCE ON THE BOLT IN THE DIRECTION TORETRACT THE BOLT WILL TEND TO FLEX THE COIL THREADES RADIALLY INWARDINTO LOCKING ENGAGEMENT WITH THE BOLT THREADS.